plus.key.addEventListener("backbutton",onback);
function onback(){
	vm.$toast("在次点击退出");
	removeEventListener();
	localStorage.setItem("kdn3",0);
	setTimeout(function(){
		plus.key.addEventListener("backbutton",onback);
	},3000)
}
function removeEventListener(){
	plus.key.removeEventListener("backbutton",onback);
}